This invention relates to a dispersant for coal into oils which is used for dispersing finely pulverized coal into an oil to produce a coal-oil mixed fuel possessing excellent stability and fluidity for an extended period of time and also to a coal-oil mixed fuel containing the dispersant.
In recent years, a quantitative limitation of petroleum reserve has strongly been recognized in addition to a steep rise in the cost of petroleum fuels which occupy the most important position in the energy sources. Thus, a long-term procurement of energy sources becomes very important in the energy policy of nations. Under these circumstances, coal which is larger in the amount of reserve as well as petroleum has again become noticed as a promising energy source. However, a coal is lumpy in shape unlike the case of liquid petroleum, it has such drawbacks that it requires a higher cost in transportation and storage and is inconvenient in handling.
In order to overcome these drawbacks in handling, extensive researches are now made in a method wherein coal is pulverized and dispersed into water or a fuel to form a slurried fuel.
From the past, investigations have been made on a coal-oil mixed fuel wherein pulverized coal has been dispersed into a fuel oil, because this mixed fuel is higher in heat value per unit weight than a mixed fuel having dispersed into water and is recognized more preferably as an energy source. In this case, a problem arises also in handling of the mixed fuel. Thus, a desirable coal-oil mixed fuel has not yet been obtained which is excellent in dispersion-stability and fluidity for a long period of time.
A large quantity of fuels is required for thermal power generation. In general, transportation and storage of such a large quantity of fuels are respectively made by using tankers and large-scale field tanks. In case a large quantity of a coal-oil mixed fuel is transported and stored in such means, a problem arises in that the pulverized coal tends to separate from the oil to permit a precipitation-and-dense-deposition phenomenon of the coal. Once such precipitation-and-dense-deposition of the pulverized coal occurs, the mixed fuel loses fluidity and makes it difficult to be unloaded from tankers or pumped out from storage tanks. Practically, therefore, it is nearly impossible to handle such mixed fuel.